High-sensitivity terahertz scanner for detection of aflatoxins in nuts and nut products

Project Summary/AbstractTerahertz waves have unique specifications that make them very attractive for non-invasive, label-freebiosensing. This is because many organic compounds have unique responses to the electromagnetic waves atterahertz frequencies. In addition, terahertz waves can penetrate through many optically-opaque environmentsas well as most of the packaging materials such as plastic, paper, etc. These great potentials make terahertzimaging/spectroscopy systems an excellent platform for high-sensitivity, high-throughput, and non-destructivedetection of aflatoxins, which can grow in various agricultural food products and cause various chronic healthproblems if consumed, including liver cancer. Aflatoxins have unique spectral characteristics at terahertzfrequencies, however the use of terahertz waves for high-throughput and high-sensitivity aflatoxin detection infood products did not seem practical before because of the low sensitivity of conventional terahertz scanners,which suffer from a trade-off between the signal-to-noise ratio (SNR) and the measurement time. For instance,to achieve a sufficiently sensitive measurement to detect the maximum allowed aflatoxin contamination levelregulated by the Food and Drug Administration (FDA) with conventional terahertz scanners, more than thousandmeasurements should be taken on the same sample to reduce the noise of the acquired data, which increasesthe measurement time significantly. In addition, most of the terahertz spectroscopy measurements should beperformed in very meticulous ways, which require specific sample preparation recipes that are not appropriatefor field settings. The proposed research addresses these limitations of conventional terahertz scanning systemsand offers a high-throughput, non-destructive, and highly-sensitive aflatoxin scanner that does not require askilled user to operate. The key innovations that enable such a high-performance aflatoxin scanner are: (1) theuse of a breakthrough plasmonic terahertz source and detector technology that offers several orders ofmagnitude higher SNR levels compared to those offered by conventional terahertz devices, (2) the use of anadvanced data analysis algorithm that is capable of direct calculation of aflatoxin concentration regardless of thetype and shape of the sample under test. As a result, the proposed terahertz scanner offers an excellentregulatory tool for high-throughput, non-destructive, non-contact detection of aflatoxins in nuts and processednut products, minimizing regulatory non-compliance risks and providing high-quality products to the public. Bythe end of the Phase I, a thorough experimental analysis will be completed on aflatoxin tablets and aflatoxin-contaminated nuts with a single-pixel terahertz scanner prototype to assess the sensitivity and specificity of theproposed scanner. In Phase II, the aflatoxin scan rate will be boosted by using focal plane detector arrays andthe use of the developed multi-pixel scanner for detection of aflatoxins will be extended to a wider range ofagricultural food products, while developing a prototype that can be used in realistic field/packaging/distributionsettings.